.nav{

        
    position:fixed; /* 绝对定位，fixed是相对于浏览器窗口定位。 */
    top:0; /* 距离窗口顶部距离 */
    left:0; /* 距离窗口左边的距离 */
    width:100%;  /* 高度 */
          height: 80px;
    z-index:99; /* 层叠顺序，数值越大就越高。页面滚动的时候就不会被其他内容所遮挡。 */
          background: #272727;
  }
  
     
  
      #navleft{
          color:#ffffff;
          font-family:myFirstFont;
          font-size: 35px;
          padding-left: 10px;
          line-height :80px;
          text-decoration: none;
      }
      .navrightpiece{
        outline: none;
          background: #272727;
              display: inline-block;
          color:#ffffff;
          text-decoration: none;
          border: 5px solid #272727;
          margin: auto;
          font-size: 25px;
              font-family: fantasy;
              text-decoration: none;
              -webkit-transition-duration: 0.3s; /* Safari */
              transition-duration: 0.3s;
              padding: 20px 100px 20px 20px;
              border-radius: 20px 0px 0px 25px;
              margin-right: 0px;
              transition: padding-right 0.5s;
              text-align: right;
              cursor: default;
      }
      .navright{
          outline: none;
          background: #272727;
              display: inline-block;
          color:#ffffff;
          text-decoration: none;
          border: 5px solid #272727;
          margin: auto;
          font-size: 25px;
              font-family: fantasy;
              text-decoration: none;
              -webkit-transition-duration: 0.3s; /* Safari */
              transition-duration: 0.3s;
              padding: 20px 20px 20px 20px;
              border-radius: 20px 0px 0px 25px;
              margin-right: 0px;
              transition: padding-right 0.5s;
              text-align: right;
              cursor: pointer;
      }
      .navright:hover{
          padding-right: 100px;
      }
      .navright:active{
          padding-right:100px;
          color:#ffffff;
                  background: #272727;
      }
      .topul{position:fixed; /* 绝对定位，fixed是相对于浏览器窗口定位。 */
    top:80px; /* 距离窗口顶部距离 */
    right:0;  /* 高度 */
    z-index:99;
      }

      
      #piece{
        margin-top: 150px;
        width: 100%;
        height: 580px;
    }

    
    #zahuo{
        width: 250px;
        height: 300px;
        margin-left: 100px;
        box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
        cursor: pointer;
    }
    #zahuoword{
        line-height: 300px;
      outline: none;
      text-decoration: none;
        font-family: YouYuan;
        text-align: center;
        font-size: 40px;
        width: 250px;
        color: #272727;
        height: 40px;
        background: #ffffff;
    }